Ultra-violet sensitive layer



. Patented Oct. 4, 1932 UNITED STATES PATENT OFFICE SAMUEL E. SHEPPARD AND HERBERT J. DIETZ, OF ROCHESTER, NEW YORK, ASSIGNORS T EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK ULTRA-VIOLET SENSITIVE LAYER .No Drawing.

This invention relates to a photo-sensitive layer, the sensitivity of which lies chiefly 1n the ultra-violet.

It is desirable for certain actinometric purposes to have a light sensitive material which reacts to the near ultra-violet rays without being appreciably affected by the rest of the spectrum. Specifically such a material may be used to demonstrate or dose the ultra-violet radiation of sunlight and of various artificial light sources, particularly those used therapeutically. It is an object of this invention to produce such a material.

We have found that thallium salts are sensitive to the ultra-violet and may therefore be used as the basis of the kind of layer described. Thallic oxalate is particularly useful and it may be prepared in a suitable colloid carrier and coated on any suitable support.

Application of the invention to the making of an ultra-violet sensitive paper is as follows:

E mample I 5 grams of thallic chloride are dissolved in 50 c. c. of water and poured with vigorous stirring into a solution of grams of potassium oxalatedissolved in 50 c. c. of gelatin solution. The mixed solutions are coated on sized paper, either by hand or by suitable machines, and then dried at 60 to 80 degrees C.

Example II 5 grams of thallic chloride are dissolved in 50 c. c. of water and poured with stirring into a solution of 10 grams of potassium Application filed May 12,

any other suitable support. A good grade of sized aper is, however, preferable as the image a ter exposure is more easilyvisible on an opaque white support.

turns rown on exposure to ultra-violet vA layer made in themanner described 5 light, and has very little sensitivity to visible v light.

What we claim is: i 1. A photo-sensitive layer sensitive primarily oxalate.

to the ultra-violet comprising thallic 2. A photo-sensitive layer 'sensitivei primarily to the ultra-violet comprising thallic oxalate and a colloid carrier. 7 f

3. A photo-sensitive element sensitive primarily to the ultra-violet comprising a support and a layer of a colloid containing thallic oxalate.

4. An actinometric paper comprising a I support of paper and a layer of a colloid containing thallic oxalate.

5. An actinometric paper comprising a .support of paper and a layer of "gelatin con York, this 7th oxalate dissolved in c. c. of 5% gum arabic solution. As before the mixed solutions are coated and dried.

The proportions as stated may be varied somewhat and other suitable colloids may be used instead of gelatin or gum arabic.

Example I I I ico 

